ParkNPark.middletier
Class ClientManagerImpl

java.lang.Object
  org.omg.PortableServer.Servant
      ParkNPark.interfaces.ClientManagerPOA
          ParkNPark.middletier.ClientManagerImpl

All Implemented Interfaces:

InvokeHandler, ClientManagerOperations

public class ClientManagerImpl
extends ClientManagerPOA

Server object that will manage communication between the client and the database.

Field Summary

(package private) PreparedStatement	checkDuplicate Statements used for duplicate message detection
private int	clientID Client's ID used for fault-tolerance
private Connection	conn Connection to the database
private int	level Level that client is in
private int	lot Lot that client is in
private static int	MAX_ATTEMPTS Maximum number of attempts when trying to execute commends on database
private static boolean	PRINT_LEVELS_STATUS
private static boolean	PRINT_LOTS_STATUS Flags used to print out the status of lots and levels
private int	seq Client's current operation sequence number used for fault-tolerance
(package private) PreparedStatement	updateSequence

Constructor Summary

ClientManagerImpl()
Create a client manager for a new client that will hold information specific to the client.

ClientManagerImpl(int clientID)
Create a client manager for an existing client that will hold information specific to the client.

Method Summary

private boolean	alreadyCompleted(int seq) Checks if the current client request has already been completed.
void	closeClientManager() Closes the client manager and frees server resources associated with it, including the client manager's activation in the server's CORBA portable object adapter
int[]	enterLot(int seq, int lot) Moves the client's car into the lot with the given lot number and returns an array of level numbers that have available spaces
void	exitLot(int seq) Removes the client's car from the lot that it is currently in
int	getClientID() Returns the client's ID, which can be used in the client manager factory's getExistingClientManager() method
int	getCurrentLevel() Returns the car's current level number
int[]	getLots() Returns an array of valid lot numbers in the system, sorted by the lot number in ascending order
int	getMaxLevel() Returns the top level number of the car's current parking lot
int	getMinLevel() Returns the bottom level number of the car's current parking lot
int[]	getOtherLotAvailability(int lot) Returns an array of other lots that have availability, sorted by lot distance such that closer lots are listed first
int	getSeqNum() Returns the client's sequence number, which can be used if the client loses track of it
int	moveDownLevel(int seq) Moves the car from its present level to the level beneath it
int	moveUpLevel(int seq) Moves the car from its present level to the level above it
private void	printLevelsStatus(String message, int seq) Print the status of all the levels in the current lot
private void	printLotsStatus(String message, int seq) Print the status of all the lots
private void	setupDatabaseConn() Set up the database connection
private void	updateClientData(int seq, int lot, int level) Updates the client table, which is used for duplicate detection.

Methods inherited from class ParkNPark.interfaces.ClientManagerPOA

_all_interfaces, _invoke, _this, _this

Methods inherited from class org.omg.PortableServer.Servant

_default_POA, _get_delegate, _get_interface_def, _is_a, _non_existent, _object_id, _orb, _poa, _set_delegate, _this_object, _this_object

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MAX_ATTEMPTS

private static final int MAX_ATTEMPTS

Maximum number of attempts when trying to execute commends on database

See Also:

Constant Field Values

PRINT_LOTS_STATUS

private static final boolean PRINT_LOTS_STATUS

Flags used to print out the status of lots and levels

See Also:

Constant Field Values

PRINT_LEVELS_STATUS

private static final boolean PRINT_LEVELS_STATUS

See Also:

Constant Field Values

clientID

private int clientID

Client's ID used for fault-tolerance

seq

private int seq

Client's current operation sequence number used for fault-tolerance

lot

private int lot

Lot that client is in

level

private int level

Level that client is in

conn

private Connection conn

Connection to the database

checkDuplicate

PreparedStatement checkDuplicate

Statements used for duplicate message detection

updateSequence

PreparedStatement updateSequence

Constructor Detail

ClientManagerImpl

public ClientManagerImpl(int clientID)
                  throws ServiceUnavailableException,
                         InvalidClientException

Create a client manager for an existing client that will hold information specific to the client.

Parameters:

clientID -

seq -

Throws:

ServiceUnavailableException - Thrown when a database exception prevented the client manager from being created successfully

InvalidClientException

ClientManagerImpl

public ClientManagerImpl()
                  throws ServiceUnavailableException

Create a client manager for a new client that will hold information specific to the client.

Throws:

ServiceUnavailableException - Thrown when a database exception prevented the client manager from being created successfully

Method Detail

setupDatabaseConn

private void setupDatabaseConn()
                        throws ServiceUnavailableException

Set up the database connection

Throws:

ServiceUnavailableException - Thrown if a problem came up while connecting to the database server or setting it up after connecting

closeClientManager

public void closeClientManager()
                        throws ServiceUnavailableException

Closes the client manager and frees server resources associated with it, including the client manager's activation in the server's CORBA portable object adapter

Throws:

ServiceUnavailableException - Thrown if the database cannot be contacted or if some other reason prevents the system from closing the client manager. The client manager remains open if this exception gets thrown

enterLot

public int[] enterLot(int seq,
                      int lot)
               throws AlreadyInLotException,
                      LotNotFoundException,
                      LotFullException,
                      ServiceUnavailableException

Moves the client's car into the lot with the given lot number and returns an array of level numbers that have available spaces

Parameters:

seq - The latest sequence number of the client

lot - The lot number to enter

Returns:

An array of level numbers that have available spaces

Throws:

AlreadyInLotException - Thrown when the client's car is already in a lot

LotNotFoundException - Thrown if the given lot number is not known to the system

LotFullException - Thrown if the given lot is full

ServiceUnavailableException - Thrown if the database cannot be contacted or if some other reason prevents the car from entering the lot

exitLot

public void exitLot(int seq)
             throws NotInLotException,
                    NotOnExitLevelException,
                    ServiceUnavailableException

Removes the client's car from the lot that it is currently in

Parameters:

seq - The latest sequence number of the client

Throws:

NotInLotException - Thrown if the car is not in a lot

NotOnExitLevelException - Thrown if the car is in a lot but is not on a permitted exit level

ServiceUnavailableException - Thrown if the database cannot be contacted or if some other reason prevents the car from exiting the lot

getClientID

public int getClientID()

Returns the client's ID, which can be used in the client manager factory's getExistingClientManager() method

Returns:

The client's ID

getSeqNum

public int getSeqNum()

Returns the client's sequence number, which can be used if the client loses track of it

Returns:

getCurrentLevel

public int getCurrentLevel()
                    throws NotInLotException,
                           ServiceUnavailableException

Returns the car's current level number

Returns:

The car's current level number

Throws:

NotInLotException - Thrown if the car is not in a lot

ServiceUnavailableException - Thrown if the database cannot be contacted or if some other reason prevents the system from returning the car's current level

getLots

public int[] getLots()
              throws ServiceUnavailableException

Returns an array of valid lot numbers in the system, sorted by the lot number in ascending order

Returns:

An array of valid lot numbers in the system

Throws:

ServiceUnavailableException - Thrown if the database cannot be contacted or if some other reason prevents the system from discovering the its defined lots

getMaxLevel

public int getMaxLevel()
                throws NotInLotException,
                       ServiceUnavailableException

Returns the top level number of the car's current parking lot

Returns:

The top level number of the car's current parking lot

Throws:

NotInLotException - Thrown if the car is not in a lot

ServiceUnavailableException - Thrown if the database cannot be contacted or if some other reason prevents the system from returning the current lot's highest level

getMinLevel

public int getMinLevel()
                throws NotInLotException,
                       ServiceUnavailableException

Returns the bottom level number of the car's current parking lot

Returns:

The bottom level number of the car's current parking lot

Throws:

NotInLotException - Thrown if the car is not in a lot

ServiceUnavailableException - Thrown if the database cannot be contacted or if some other reason prevents the system from returning the current lot's lowest level

getOtherLotAvailability

public int[] getOtherLotAvailability(int lot)
                              throws LotNotFoundException,
                                     ServiceUnavailableException

Returns an array of other lots that have availability, sorted by lot distance such that closer lots are listed first

Parameters:

lot - The lot to get lot distances from

Returns:

An array of other lots that have availability

Throws:

LotNotFoundException - Thrown if the given lot number is not known to the system

ServiceUnavailableException - Thrown if the database cannot be contacted or if some other reason prevents the system from discovering the availability of other lots

moveDownLevel

public int moveDownLevel(int seq)
                  throws NotInLotException,
                         AtBottomLevelException,
                         ServiceUnavailableException

Moves the car from its present level to the level beneath it

Parameters:

seq - The latest sequence number of the client

Returns:

The level number that the client's car is now on

Throws:

NotInLotException - Thrown if the car is not in a lot

AtTopLevelException - Thrown if the car is already on the lowest level

ServiceUnavailableException - Thrown if the database cannot be contacted or if some other reason prevents the car from moving to the lower level

AtBottomLevelException

moveUpLevel

public int moveUpLevel(int seq)
                throws NotInLotException,
                       AtTopLevelException,
                       ServiceUnavailableException

Moves the car from its present level to the level above it

Parameters:

seq - The latest sequence number of the client

Returns:

The level number that the client's car is now on

Throws:

NotInLotException - Thrown if the car is not in a lot

AtTopLevelException - Thrown if the car is already on the highest level

ServiceUnavailableException - Thrown if the database cannot be contacted or if some other reason prevents the car from moving to the next highest level

alreadyCompleted

private boolean alreadyCompleted(int seq)
                          throws ServiceUnavailableException

Checks if the current client request has already been completed.

Parameters:

seq -

Returns:

Throws:

ServiceUnavailableException

updateClientData

private void updateClientData(int seq,
                              int lot,
                              int level)
                       throws ServiceUnavailableException

Updates the client table, which is used for duplicate detection.

Parameters:

seq -

lot -

level -

Throws:

ServiceUnavailableException

printLotsStatus

private void printLotsStatus(String message,
                             int seq)

Print the status of all the lots

Parameters:

message - The message to display with the status

seq - The client request sequence number

printLevelsStatus

private void printLevelsStatus(String message,
                               int seq)

Print the status of all the levels in the current lot

Parameters:

message - The message to display with the status

seq - The client request sequence number